Oxidizing hydrocarbons in the presence of triggering agents



Feb. 14, 1967 J, JONES ET AL OXIDIZING HYDROCARBONS IN THE PRESENCE OF TRIGGERING AGENTS Filed March 9, 1960 LIFT FLUID Jennmgs H Jones to Merrell R. Fenske PotenfAtrorney United States Patent 3,304,329 OXIDIZING HYDROCARBONS IN THE PRESENCE OF TRIGGERING AGENTS Jennings H. Jones and Merrell R. Fenske, State College,

Pa., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Mar. 9, 1960, Ser. No. 13,842 4 Claims. (Cl. 260-592) This invention relates to the partial oxidation of organic compounds. More specifically, the invention concerns the noncatalytic partial oxidation and dehydrogenation of hydrocarbons and oxygenated'hydrocarbons at elevated temperaturesby the use of certain triggering agents. T o be specific, the partial oxidation and dehydrogenation of certain olefinic and parafiinic compounds, especially those that are highly substituted with methyl and/or ethyl groups, that are difficult to oxidize and dehydrogenate at relatively lower temperatures, are effected at such temperatures by adding a small amount of a triggering agent to the feed.

It is well known in the art to partially oxidize various hydrocarbons and substituted hydrocarbons by contacting them with oxygen at elevated temperatures. Many hydrocarbons are oxidized to valuable oxygenated compounds with relative ease, whereas others are extremely difiicult to oxidize so that a reasonable yield or selectivity is obtained. The very low molecular weight hydrocarbons, such as methane, ethane, ethylene, propane and propylene are rather diffic-ult to oxidize and require extremely severe conditions including high temperatures, e.g. 600 C., and often some catalytic action. The same is true of the highly methylated and ethylated lower molecular weight olefins and paraflins, and the aromatic compounds having lower molecular weight alkyl groups, e.g. ethyl. The more readily oxidizable compounds include the medium to higher molecular weight hydrocarbons such as hexane, heptane, octane and so on, as well as the cycloaliphatic compounds of one or more rings, such as cyclohexane, and some of the naphthenes.

The partial oxidation of parafiins and aromatics has heretofore been carried out in both the liquid and the vapor phase. Liquid phase oxidation has many drawbacks and usually requires the presence of specific solvents to obtain directional oxidation toward desirable products. On the other hand, conventional vapor phase partial oxidation techniques are quite sensitive to temperature and surface. While a certain minimum temperature is required to initiate the reaction, excessively high temperatures will cause over-oxidation resulting in the production of carbon monoxide and water.

It has now been found that the more difficult to oxidize hydrocarbons and oxygenated hydrocarbons, e.g. alcohols, can be partially oxidized and dehydrogenated at substantially lower temperatures by the use of certain triggering agents which comprise compounds that are more easily oxidized. The invention has special application to the partial oxidation and dehydrogenation of lower alkyl aromatics, such as ethylbenzene, and saturated or unsaturated aliphatic compounds that have internal double bonds and/or are highly substituted with lower alkyls, especially methyl and ethyl groups.

The particular triggering agent selected will vary according to the composition of the feed to be oxidized. Generally speaking, it will be found that straight chain aliphatic and cyclic compounds having 4 to carbon atoms per molecule are useful. Suitable triggering agents include C to C cyclic paraffins, such as cyclohexane, C to C olefins such as octene-Z, pentene-l, hexene-l and butene-l, Ct, to C parafiins such as n-butane, n-hexane, isoheptane, and n-octane, and C to C oxygenated com- 3,3tl4,329 Patented Feb. 14, 1967 pounds such as methylethyl ketone, valeraldehyde, heptaldehyde, C epoxides and hexanol-l. The preferred triggering agents are aliphatic compounds that contain 4 to 8 carbon atoms per molecule. The compounds used to improve the yield of useful products and reduce the oxidation threshold temperature should contain at least 30% methylenic carbon atoms, i.e. CH and CH but they should not have more than 30% of their carbon atoms in the form of methyl or ethyl substituents, i.e. methyl and ethyl branches.

While alpha olefins are useful triggering agents for certain oxi-dations, e.g. the oxidation of olefins having internal unsaturation, normal paraifins are the preferred triggering agents for most feeds because of their case of oxidation and low cost. They not only lower the oxidation threshold temperature of diificult to oxidize hydrocarbons but they frequently increase the rate of oxidation. In some instances they behave as catalysts in that they need not be replaced with fresh material.

In accordance with the present invention, a relatively low concentration of the triggering agent is maintained in the reaction mixture to effect partial oxidation and dehydrogenation at comparatively lower temperatures, i.e. in relation to processes in which no triggering agents are used. While reaction temperatures of up to 600 C. may be employed, it will be found that most reactions can be carried out at temperatures of 300 to 500 C.

The amount of triggering agent added to the reaction zone should be minor in relation to the feed, eg it should not exceed about 20 mole percent of the feed if substantial contamination is to be avoided. While concentrations as low as 1 or 2 mole percent will have some beneficial effect on the reaction, in general the preferred concentration of triggering agent is between 5 and 15 mole percent. It is advantageous to use small quantities of the triggering agent, i.e. not more than 10 or 11 mole percent in order to assist in'the recovery of the desired products. If the products are severely contaminated with the triggering agent or its oxidation products, difficult and expensive separation techniques will be necessary.

Among the more difiicult to oxidize feeds that may be used in the present invention are the C to C organic compounds, especially C to C hydrocarbons and oxygenated hydrocarbons that contain at least 1 methyl or ethyl substituent and/or an internal double bond. For instance, the feed may comprise C toC lower alkyl aromatics, such as toluene, trimethylbenzene, oand p-xylene, ethylbenzene, C to C aliphatic olefins which may be highly methylated and/or ethylated such as trimethylethylene, butene-2, propylene and ethylene or C to C parafiins which also may be highly alkylated, such as icobutane, ethane, propane and isopentane. Other highly methylated and/ or ethylated higher molecular weight aliphatics, such as triptane, 2,4,6,8-tetramethylnonane and 2,4,6,8,10,l2,l4-heptamethylhexadecane may also be used as feed in this process. Suitable oxygenated hydrocarbon feeds include highly branched C to C oxo alcohols, tbutyl alcohol and diflicult to oxidize carbonyl compounds.

In order to recover the largest yields of commercially useful products, e.g. acetaldehyde, benzaldehyde and styrene from the ethylbenzene, it is necessary to carefully control the oxidation of the feed. Multiple injection of oxygen at special intervals, as compared to injecting all the oxygen at a single stage of the reaction, has been found helpful in repressing conversion of the feed to unwanted carbon oxides.

The required temperature control can best be effected by the use of relatively cool solid particles evenly dispersed throughout the reaction zone which remove the heat of reaction and prevent it from reaching an inflammable stage. The solids permit the safe use of larger r 3 proportions of oxygen in the reaction mixture than where other cooling means are employed.

In one technique known as the raining solids method, the reactor is essentially a vertical open tube, except that a sufficient amount of relatively cool, finely divided inert'solids is dispersed evenly across and rained down through the reaction zone to remove the reaction heat and maintain the desired reaction temperature. The proportion of solids needed for good temperature control amounts to from about 0.05% to about 10%, preferably about 0.1% by volume of the reaction zone, depending on the oxygen-feed ratio, the nature of the feed, the kind and size of solids, the'solids/oxygen ratio, etc. It is known that inert solid surfaces tend to inhibit oxidation and may completely arrest it if their amount becomes excessive. It is for this reason, for instance, that it has been impractical to carry out the desired non-catalytic oxidation with conventional dense fluidized beds of finely divided solids which otherwise constitute very effective heat transfor media. The finely dispersed cooling solids employed in the present process do not have this undesirable effect, but rather their use gives one maximum control of the reaction.

The drawing shows one type of reactor, in which raining solids are employed to control the reaction tern perature, that is particularly suitable for the novel oxidative dehydrogenation reactions of the present invention.

A highdegree of conversion, e.g. from 20 to 50% per pass, is an important feature of this invention. The desired high conversion is accomplished by injecting oxygen, usually at a multiplicity of points, into the reaction zone in total amounts exceeding 0.3 mole per mole of oxidizable feed, or by' partial recycling of the conversion products. In most cases the oxygen/ feed mole ratio will be in the range between about 0.5 to 5, depending on the molecular Weight of the feed and desired conversion. Generally speaking, the higher molecular weight compounds will' require relatively high oxygen/ feed mole ratios for a comparable degree of conversion. Excessive oxidation or degradation into oxides of carbon is prevented or minimized by the heat control technique of this invention which assures a high rate of heat removal, short contact time, and uniform flow without back mixgig or internal recycling such as occurs in dense fluidized eds.

The oxidant is preferably oxygen, but may be air, enriched air, ozone, or other oxygen-containing gas, such as a mixture of oxygen and steam. The various vaporous feed stocks oxidize with different rates, and the temperatures to initiate reaction are diiferent, but easy to deter mine. If the reaction tends to be too fast or violent, it is frequently better to use an oxygen-diluted oxidant such as air, or oxygen-steam mixtures. Of course, the use of gaseous diluents is avoided where possible, in order to keep the size and complexity of the gaseous recovery System at a minimum.

The pressures used may range from about or p.s.i.g. to about 100 or 200 psig The reaction temperatures used are above 300 C. and below 650 C., usually in the range between about 400 and 500 C. For instance, in a typical case the solids may be at a temperature of perhaps 300 to 450 C. when injected into the reaction zone' but the maximum temperature in the reaction zone may be 20 to 100 C. higher than the initial temperature of the solids.

The actual time required to react oxygen with the vaporous feed is short, usually a few seconds or fraction of a second. However, since the desired oxidation products are usually stable thermally for at least a few seconds at the reaction temperatures involved, the residence time in the reactor may range from one second. upward, e.g. 3 to or seconds. Of course, it is imperative that the temperature be kept throughout within tolerable d limits and it is desirable to remove the reaction products as rapidly as possible.

The solids used in the reactor to control the reaction and pick up the reaction heat may be silicious or aluminiferous materials such as Ottawa sand, glass beads, spent clays, quartz, fused alumina, mullite, coke, and the like. These solids are essentially inert toward the feed stock, i.e., they are not needed as catalysts to initiate the oxidation reaction. Their purpose is to moderate the reaction zone with respect to temperature, to prevent the formation of local hot spots, to slow down and spread out the active reaction zone, and to assimilate the heat of reaction so that this heat can, in turn, be removed from the solids in another operation. They may be fed to the reaction zone in a ratio of about 5 to 50 lbs. per pound of hydrocarbon feed, e.g. 5 to 35 lbs/lb. Increasing solids concentrations and large amounts of surface in particular tend to slow down the reaction and may promote the formation of carbon dioxide at the expense of more desirable products. In general, the individual size and shape of the solid particles are such that they can be fluidized, but they should not be so small that they are readily entrained in the gases, or such that they are not amenable to separation from the reaction gases by conventional solid-gas separators such as cyclones. They should also resist attrition. The size of the solid particles usually ranges from about 50 to 200 microns. Particles of 100 to 300 microns show low entrainment in the gas as well as good flow features and may therefore be preferred. The size of the particles may in some instances constitute a useful process variable since some of the relatively difficult oxidations, such as that of ethane or n-butane, can be performed satisfactorily with solids having a particle size of 250 to 350 microns whereas an equal weight of smaller particle sizes tends to inhibit the reaction unduly, presumably because of the increased amount of surface area present. Conversely, a relatively small particle size may be preferred in the case of easily oxidizable hydrocarbons when one desires to slow down the reaction. Coarse solids also permit higher gas velocities and hence shorter gas residence times in the reactor.

Referring to the drawing, a suitable reactor may consist of a vertical cylindrical shell reaction chamber 1 and an expanded top 2, fabricated to withstand temperatures up to about 650 C. and pressures to about 200 to 400 p.s.i.g. It is provided with openings 3, 4-, and 5. In the upper part of the expanded section 2 is a fluidized, or partially fluidized bed 6 of fused alumina or similar inert solids, and a similar bed of the same solids exists at the bottom, 7. Solids in upper bed 6 are metered by one or more valves 8. The solids thus can be fed and flow downward, under essentially free-fall conditions into space 13. About 25 pounds of fused alumina, of about 300 micron particle diameter, for instance, can thus be rained downward countercurrently to the ascending'reaction gases per pound of feed stock introduced through inlet 3. These falling solids impinge on grid 12 which serves to break up any clusters of the solids and disperse them still more so they are able to rain or fall down throughout reaction space 13 in a highly dispersed, uniformly distributed manner. The solids collect at the bottom of the reactor to form a dense bed 7. The upward linear gas velocity in the reaction space is desirably in the range of about 0.5 to 10 ft./sec., e.g. 3 ft./sec.

Vaporized feed consisting of mole percent ethylbenzene and 10 mole percent hexane is introduced into reaction chamber 1 through feed line 3. If desired, part of the feed may be introduced directly into bed 7 to increase fluidization or to produce feed preheating or vaporization. Steam or some other stable fluid is introduced through lines 16 and 19 and nozzle 22 to lift the solids through line 23 which is preferably flared at the bottom. A part of the lift fluid is introduced into the fluidized bed 7 via lines 20 to keep the bed fluidized. Also, especially if a liquid or partially liquid lift medium tion further.

such as water or wet steam is used, it can be sent through line 18 and coil 21 to be vaporized and preheated While thus simultaneously cooling bed 7. Of course, when the feed itself is sufliciently stable, it may be used as the lift fluid instead of any extraneous material.

At the top of pipe 23 the solids are disengaged from the lift vapors and fall downward to constitute bed 6. The vapors emerging from the top of pipe 23 flow around baflle 24 and out through opening 5. A high degree of separation efficiency is usually not necessary since both the solids and the vapors eventually pass from the top of the reactor into reaction space 13. However, a cyclone may be used, if desired, to separate entrained solids' from the vapors leaving through pipe 5.

The hot fluidized solids entering the flared base of pipe 23 vaporize any liquid introduced via line 19. In this way the solids are cooled and the necessary vapors are generated to propel the solids up through lift pipe 23. Nozzle 22 serves to aspirate the solids into the base of pipe 23.

As mentioned before, the feed to be oxidized enters the reaction chamber vessel 1 at inlet 3 and flows upward through reaction space 13. In this way it flows countercurrently to the descending, dispersed rain of particulate solids issuing around valves 8 and passing downward through grid 12. During their fall through vessel 1 and reaction space 13 these solids rapidly pick up the heat generated in space 13.

Oxygen enters pipes 33 which are placed from 1 to 5 feet apart along the vertical length of reaction zone 13. These pipes comprise substantially uniplanar coils, and have a large number of holes or slots on their underside so the oxygen can be distributed uniformly throughout the whole cross section of vessel 1. These coils 33 also serve to redisperse and redistribute the raining solids.

At or near oxygen inlet coils 33 the reaction of the oxygen and vaporous feed fast occurs. The heat thereby liberated has to be promptly assimilated, or reaction temperatures rise to intolerable levels. The raining, relatively cool solids accomplish this quickly because of their intimate contact with the entire body of reacting gases.

Multiple oxygen injection is used to control the reac- That is, the oxygen is added in relatively small increments so it can react, and the reaction heat be absorbed by the solids, before the next increment of oxygen is added. By thus keeping the local mole ratio of oxygen to hydrocarbon between about 0.1 and 0.5, overall mole ratios of oxygen to fed as high as 5 can be employed.

The vaporous reaction products flow upwardly through enlarged section 2 where the gas velocity is decreased to allow entrained solids to drop back into vessel 1. The vapors then leave via line 4, are combined with the lift gas and recovered. Of course, in commercial practice it may be preferred to recover the oxidized product separately from the lift gas.

The following description relates to the control of the oxygen, the feed stock, the solids streams, and of the reaction heat.

The solids in upper bed 6 desirably are at as low a temperature as possible to facilitate rapid cooling of the gases, but usually hot enough to permit establishing the desired reaction temperature in reaction space 13. For instance, the solids in bed 6 may be at 350 to '400" C., and become heated up to the desired reaction gas pressure in pipe 34 operates a pilot valve which in turn operates a conventional or hydraulic cylinder (not 6. shown) attached to the upper end of valves 8 to move them up and down.

The temperature of lower bed 7 is measured by thermocouple 36. This measurement can be used to control the proportion of the lift medium which is allowed to pass through coil 21 so as to offset the necessary amount of cooling. p I

The oxygen fed to coils 33 is likewise controlled to comprise the desired oxygen-to-feed molal ratio, e.g. 0.8 total, injected in four equal increments.

The temperature of bed 6 is controlled in part by the proportions -of lift gas and solids flowing through lift pipe 23, by the amounts of liquid-lift medium flowing through line 19 and to vaporizer 21, and by the temperature of bed 7. Valve 38 may be used to apportion the flow of vaporizable liquid through vaporizer 21. If desired, an additional heat transfer coil may be positioned in bed 6 or bed 7 or both to provide further heating or cooling. Such cooling maybe particularly appropriate when a normally gaseous. lift medium is being used.

While the foregoing description relates to the preferred operation involving countercurrent flow of feed vapor and solid, the illustrated apparatus can also be operated with concurrent flow. In such an event, the feed 'is introduced through opening 4 and passed downward through reaction space 13 concurrent with the solids falling through grids 12,-the.product'beingwithdrawn through line 3. In this case the temperature of the solids in bed 6 is maintained ,at about 400 C. and heat of reaction is preferably taken out not only in dense beds 6 and 7, but also by cooling coils (not shown) positioned in reaction space 13, in order to prevent the reaction temperature from exceeding the permissible maximum. Moreover, a horizontal concurrent flow reactor may be employed provided the inert finely divided solids are evenly dispersed throughout the reaction zonein a concentration of about 0.05 to 10 volume percent of solid per volume of reaction space.

The following examples will further illustrate the nature and advantages of thisinvention. In the absence of contrary indications ratios and percentages of materials are expressed on a weight basis.

Example 1 TABLE I.VAPOR PHASE OXIDATION OFETHYLBEN- ZENE INITIATED WITH n-HEXANE Feed conversion, percent 24.5 Oxygen conversion, percent 50.9 Oxygen/feed mole ratio (based on 0 charged) 0.69 Lb. 0 lb. of hydrocarbon feed (based on O consumed) 10.8 Contact time, seconds 5 Solids rate, lb./g-mole O reacting 20.7 Average reaction temp., C. 430 Charge data:

Feed charged, grams 846 Oxygen charged, grams 179 Water as solids lift, grams 1867 Duration of experiment, minutes Product data:

Organic layer, grams 778 Water layer (total), grams 1932 7 CH0. in non cond. gas, grams 129 Vol. of dry gas at S.T.P., cu. ft. 4.1 Analytical data on organic layer:

Carbonyls (g. /100 g. sample) 1.2 Bromine No. (g. -br./l00 g. sample) 19 Solub. in 85% H PO vol. percent 11 TABLE II.PRODUCTS FROM ETHYLBENZENE (HEX- ANE INITIATED) OXIDATION Lbs/100 lbs. of

Product: ethylrlelligg Styrene 25 Benzaldehyde 29 Acetophenone 6 Example 2 The ability of n-butane to initiate the oxidation of 2-butene in a raining solids reactor is shown by the data in Table HI. Thus, whereas pure Z-butene reacts only slowly with oxygen in the presence of dispersed fine particulate solids (300 microns fused zircon silicate) at temperatures below about 460 C., the addition of a small proportion of n-butane to the Z-butene feed initiates the reaction of the Z-butene at a temperature as low as about 380 C.

TABLE IIL-VAPOR PHASE OXIDATION OF 2-BUIENE INITIATED WITH n-B UTANE Run No 1 2 QFButcne Z-butene, 89 wt. Feed {(only) n-Butane, 11 wt.

Feed Conversion, percent 7 32 Oxygen Conversion, percent 26 95 Oxygen/Feed mole ratio:

Based on 02 charged O. 35 0. 46 Based on O; reacted" O. 10 0. 44 Lb 0 /100 lb. of feed (has 02 consumed) 6. 4 24. 5 Ave. reaction temp, C 460 410 Contact time, seconds 6 6 Solids Rate, lh./hour 21 26 Solids Rate, lb./g.-mo1e 0 reacting 64 17 Products, Ill/100 lb. of 2butene reacted:

Acetaldehyde 25. 7 Formaldehyde. 5. 7

ted

Other organic oxygena Ethylene plus propylene 1. 2 4. 4 Other olefins and diolefins 23. 4 4. 3 Carbon monoxide 6. 9 26. 6 Carbon dioxide 53. 2 10. 4

In run 1 in Table III in which pure Z-butene was oxidized at a temperature of 460 C. only 7% of the hydrocarbon and only 26% of the oxygen reacted. On the other hand, in run 2 in Table III in which n-butane was added as an initiator, the oxygen conversion was 95% and the Z-butene conversion was 32% although the reaction temperature was only 410 C. Another advantage in using n-butane as an initiator is apparent on examining the products of the two runs in Table III. For instance, in run 2 Where an initiator was used the yield of useful oxygenated products was greater and the production of undesirable carbon dioxide was lower. Furthermore, a small proportion of n-butane was produced in run 2. That is, the butane employed as an initiator was not consumed in the reaction and a slight amount (over that fed) was generated. The n-butane thus acted like a catalyst. This was an entirely unexpected result. Moreover, although there were no C hydrocarbons in the feed a small proportion of pentenes was produced during the reaction. Thus, the reactions occurring in the reaction zone include the building up of carbon chains as well as their degradation.

Example 3 The C fraction obtained as elf-gas from catalytically cracking a MidContinent virgin naphtha makes an ideal feed stock for the process described in Example 2. The composition of a typical C4: fraction from catalytic cracking is as follows:

Composition: Vol. percent Z-butenes 64 l-butene 5 Isobutene 2 n-Butane 26 Isobutane 3 The oxidation of such a feed occurs readily at a temperature of 400 C. and gives products similar in nature and composition to those indicated in the second case under Example 2.

Example 4 l-butene is used to initiate the oxidation of Z-butene. Thus, a mixture of 1- and Z-butenes containing 10% of the l-isorner is reacted at 400 C. (at which temperature and conditions pure Z-butene does not undergo any appreciable reaction) to give products similar to those illustrated in Example 2.

Example 5 Pure trirnethylethylene reacts only slowly when subjected to vapor phase oxidation at a temperature of about 500 C. to yield the products shown in Table IV:

Contact Time, seconds 5 5 Products, lbs./ lbs. Trimethylethylene Reacted:

Carbon Monoxide 12 17 Carbon Dioxide. l5 5 Isoprene 21 5 Other Paraflins plus Olefins 23 7 Acetaldehyde 10 15 Methyl Alcohol. 3 5 Acetone 2O 30 Epoxides, C5.-- 1 3 Other oxygenated Compds 30 40 However, on adding about 10% isopentane to the olefin, the reaction occurs readily at 400 C. to yield an increased proportion of oxygenated products. The same reactor and cooling solids used in Example 1 were employed here.

Example 6 n-Pentane, n-butane, isobutane, n-hexane, or other simply branched alkanes may be substituted for isopentane in run 4 of Example 5. Similar results are obtained.

Example 7 The addition of 5% of n-hexane to isooctane undergoing oxidation halved the contact time required to attain equivalent oxygen conversion without adversely changing the nature of the products formed. This is shown by the data in Table V.

TABLE v Run No 6 d o "(r (1 95% Isooctane" Fee x1 lze ig? 5% n-Hexane It was also observed that the use of n-hexane as an initiator lowered the reaction temperature necessary to attain equivalent feed conversion.

Example 8 The addition of 5% of n-hexyl alcohol to isooctane undergoing oxidation also halved the contact time required to attain equivalent oxygen conversion.

Example 9 The addition of 5% of heptaldehyde to ethylbenzene was effective in lowering the threshold temperature of the oxidation and giving an increased production of oxygenated compounds.

Example 10 The addition of 10% of n-butane to propylene also lowered the threshold temperature and increased the conversion to oxygenated compounds, such as formaldehyde and acetaldehyde.

It is not intended to restrict the present invention to the foregoing examples which are merely given to demonstrate some of the embodiments of the invention. It should only be limited to the appended claims in which it is intended to claim all of the novelty inherent in the invention as well as the modifications and equivalents coming within the scope and spirit of the invention.

What is claimed is:

1. A process for oxidizing a lower alkyl aromatic compound that normally requires the use of severe conditions including high temperatures which comprises contacting about 85 to 99 mole percent of said lower alkyl aromatic compound in vapor form with about 1 to mole percent of a C C more easily oxidizable organic compound selected from the group consisting of hydrocarbons and hydroxy, carbonyl and epoxide substituted hydrocarbons that has at least 30% methylenic carbon atoms, but not more than 30% of its carbon atoms in the form of alkyls selected from the group consisting of 10 methyl and ethyl substituents and a free oxygen-containing gas, passing the resulting mixture through a reaction zone at a temperature between about 300 and 650 C., also passing through the reaction zone evenly dispersed 5 finely divided inert solids that are at a temperature below the maximum temperature in the reaction zone said solids being present in a concentration of about 0.05 to 10 volume percent of solid per volume of reaction space and sufiicient to maintain the average temperature in said 10 reaction zone below 650 C., the mixture being passed through the reaction zone at a rate such that the residence time of the mixture in the reaction zone is not more than seconds, and separating the reaction products from the mixture.

2. A process for oxidizing a difficultl oxidizable C to C aromatic hydrocarbon which is substituted with at least one alkyl selected from the group consisting of methyl and ethyl su'bstituents, which comprises contacting a mixed feed consisting of about 85 to 99 mole percent 20 of said diflicultly oxidizable hydrocarbon and 1 to 15 mole percent of a C to C easily oxidizable normal paraflin, in vapor form with a free oxygen-containing gas such that the local mole ratios of free oxygen to oxidizable feed are about 0.1 to 0.5, pasing the resulting mixture upwardly through a reaction zone at a temperature between about 350 to 500 C., also passing through the reaction zone in a free-fall condition evenly dispersed finely divided inert solids that are at a temperature below the maximum temperature in the reaction zone, said solids being present in a concentration of about 0.05 to 10 volume percent of solid per volume of reaction space and sufiicient to maintain the average temperature in said reaction zone below 500 C., the mixture being passed through the reaction zone at a rate such that the residence time of the mixture at the elevated temperature is between about 1 and 10 seconds, and separating the unsaturated and organic oxygen-containing compounds from the oxidized mixture.

3. A process according to claim 2 in which the oxygencontaining gas is substantially pure oxygen.

4. A process according to claim 2 in which the difiicultly oxidizable hydrocarbon is ethylbenzene and the easily oxidizable paraffin is normal hexane.

LEON ZITVER, Primary Examiner. CHARLES B. PARKER, Examiner.

LORRAINE A. WEINBERGER, D. D. HORWITZ,

Assistant Examiners. 

1. A PROCESS FOR OXIDIZING A LOWER ALKYL AROMATIC COMPOUND THAT NORMALLY REQUIRES THE USE OF SEVERE CONDITIONS INCLUDING HIGH TEMPERATURES WHICH COMPRISES CONTACTING ABOUT 85 TO 99 MOLE PERCENT OF SAID LOWER ALKYL AROMATIC COMPOUND IN VAPOR FORM WITH ABOUT 1 TO 15 MOLE PERCENT OF A C4-C20 MORE EASILY OXIDIZABLE ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDROCARBONS AND HYDROXY, CARBONYL AND EPOXIDE SUBSTITUTED HYDROCARBONS THAT HAS AT LEAST 30% OF ITS CARBON ATOMS IN THE ATOMS, BUT NOT MORE THAN 30% OF ITS CARBON ATOMS IN THE FORM OF ALKYLS SELECTED FROM THE GROUP CONSISTING OF METHYL AND ETHYL SUBSTITUENTS AND A FREE OXYGEN-CONTAINING GAS, PASSING THE RESULTING MIXTURE THROUGH A REACTION ZONE, AT A TEMPERATURE BETWEEN ABOUT 300* AND 650*C., ALSO PASSING THROUGH THE REACTION ZONE EVENLY DISPERSED FINELY DIVIDED INERT SOLIDS THAT ARE AT A TEMPERATURE BELOW THE MAXIMUM TEMPERATURE IN THE REACTION ZONE SAID SOLIDS BEING PRESENT IN A CONCENTRATION OF ABOUT 0.05 TO 10 VOLUME PERCENT OF SOLID PER VOLUME OF REACTION SPACE AND SUFFICIENT TO MAINTAIN THE AVERAGE TEMPERATURE IN SAID REACTION ZONE BELOW 650*C., THE MIXTURE BEING PASSED THROUGH THE REACTION ZONE AT A RATE SUCH THAT THE RESIDENCE TIME OF THE MIXTURE IN THE REACTION ZONE IS NOT MORE THAN 20 SECONDS, AND SEPARATING THE REACTION PRODUCTS FROM THE MIXTURE. 